1) Percent fatty tissue of the breast is plotted against age with a composite polystyrene-water phantom. These results are then converted to the skin doses against ages which are in proportion to the MAS required in producing 1.0 film density. 2) The mesurements of diagnostic quality are carried out with following test objects : a smallpiece of the paraffin block of the mammary carcinoma which containes 30 minute calcific deposits ranging from 90〜400μ in diamiter. The Value of O.T.F. is multiplied by one-half the corresponding contrast of 0.2mm-A1 (1/2ΔD) in order to account for the detail visibility under varring technical factors A 0.25mm-A1 resalution test chart is then made by that thonght, and good agreement is seen between the two measurements. The results thus obtained indicate that the combination of the coarcer grain industrial film and larger focal spot size is better in detail visibility than the opposite combination because of its higher subject contrast. Screen technics with fine detail screens such as BS and FS in back only, or in combination have no negative effect on visual detection if the kvp is reduced with respect to the screen speed. 3) Technics of manmography are extended to soft tissue roentgenography of the thyroid. An image of thyroid Carcinoma can be Visualized in our tangential view by applying the screen system.

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Soft-tissue radiography is mainly applied to the part of low contrast regions of human body. One of the most Popular one is mammography which is essential for overstep the boundary or palpation. Many authors have reported the studies of enlargement radiography, tomography and fluorography applied to the radiogram. In false diagnosis point of view, foreign authors have reported only 10% in T_1 group, but now in japan generaly 50% amounts in the same group. None of their reports clarified racial factors of the shape, the size and the like at all. The purpose of this paper is to investigate the situation as follow; 1) Appropriate technique for mammograthy to japanese women. 2) X-Ray apparatus factors and the image qualities of the radiogram. 3) Compensated method and bury-suction compensated method with alchol.

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Recently, radiography of the breast has become activity in Japan. But that standardization is not yet established at presnt. For this purpose, we tried experiments about following some technical problems. (1) Characteristics of various X-ray films with or without screen on the low voltage. (2) Relation between the resolution and the exposure dose to the patient. (3) Variation of X-ray tube focal spot size with exposure data. (4) The others, about several factors for X-ray image. Also, In this article refers to the characteristice of our trial high speed rotating anod soft X-ray tube unit "CIRCLEX 0.5/1 U35YN-23".

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